Chapter 37 Restless Legs Syndrome Morbidity: Sleep and Quality of Life
Aside from the increased risk of death for patients with both restless legs syndrome (RLS) and end-stage renal disease (see Chapter 25), RLS has no known impact on mortality. But the symptoms associated with the disorder adversely affect several key aspects of daily life. We often assume that we already know the impact of these symptoms on functioning and therefore focus mostly on describing and evaluating the symptoms rather than looking at their impact on the patient’s life. Indeed, this approach has been taken for RLS, and even as late as 2003 there had been very few published studies on the morbidity of RLS. This turns out to be particularly regrettable for RLS. For the morbidity may provide an important, if not the primary, justification for treatment of the disorder. The rationale for treatment then lies not merely with reducing the symptoms but also with reducing the impact they have on the patient’s life.
Morbidity From Sleep Disturbance of Restless Legs Syndrome
RLS classification as a sleep-related disorder1 emphasizes the sleep disturbance characterizing the disorder. By definition, rest provokes RLS symptoms and it can be seen as a disorder of that quiet drowsy state of waking (the predormitum) that precedes sleep but may occur at other times during the day. RLS will therefore generally disrupt sleep, and indeed, the population-based surveys indicate more than 75% of those with at least moderate RLS symptoms complain of significant sleep disturbance caused by their RLS.2 It appears that some who have very mild RLS do not have any sleep complaint. In such cases, the patient appears to fall asleep fast enough to avoid developing significant symptoms while lying in bed; the longer periods of sitting in the evening, however, cause considerable distress. Most RLS patients, though, complain of interrupted sleep, insufficient hours of sleep, and difficulty falling and staying asleep. Curiously, only a minority complain of daytime sleepiness.2 Figure 37-1 shows the range of RLS effects on sleep onset and sleep awakenings for those with moderate to severe RLS symptoms. These have been confirmed by polysomnographic studies of RLS patients3 and by reports from clinical trial populations showing decreased total sleep times, decreased sleep adequacy, and increased sleep disturbance, which are largely improved by treatment with the dopamine agonist ropinirole.4,5 Sleep efficiency for the more severely affected RLS patient drops below 60% with less than 5 hours a sleep a night for most nights,6 producing what is probably the most extreme chronic sleep loss of any sleep-related disorder; yet, there have been few studies evaluating the effect of this sleep loss.
Profound daytime sleepiness should develop with this level of sleep loss, but surprisingly RLS patients generally do not report falling asleep in the daytime at inappropriate times (e.g., sitting in a car at a red light, talking on the telephone). Thus, the question arises—Aside from the discomfort from not sleeping, do RLS patients have any adverse effects from the sleep loss? That is, do RLS patients show changes in mood, cognition, attention, or pain perception generally associated with significant sleep loss? Unfortunately, to date, this has hardly been studied at all. Saletu and colleagues7 found no excessive sleepiness or vigilance decrement for untreated RLS patients compared with control subjects. Pearson and colleagues,8 however, did find that untreated RLS patients had decreased cognitive performance in the morning on verbal fluency and trail making tests consistent with the prefrontal cognitive effects shown for one night’s of total sleep deprivation.9 Aside from these studies, we know very little about the effects of the sleep disturbance in RLS. It looks as if it produces an awake, but possibly fatigued, individual with some disturbance of prefrontal cognitive functioning, a type of dysfunction also shown with attention deficit disorder.10
Quality of Life Measures Used in Restless Legs Syndrome
Three basic types of QoL measurements have been developed: general QoL assessments, disease-specific QoL measures, and judgments or recording of critical life-activities or events. The general QoL assessments usually focus on providing a broad-based assessment of health-related impacts on QoL. Several instruments have been developed to provide this type of QoL assessment, including the Nottingham Health Profile, the Sickness Impact Profile, and the 36-item Short-form Health Survey (SF-36). The most commonly used and best standardized is the Medical Outcomes Study11 SF-36,12,13 which has been shown to have very good psychometric properties when used in a patient population.14 The SF-36 also comes in two shortened forms: the SF-1215 and the SF-8.16 The SF-36 provides scores in eight dimensions and a summary score for four dimensions covering physical health (physical functioning, role physical, pain, and general health) and four covering mental health (role emotional, vitality, social functioning, and mental health).
Quality of Life for Untreated Restless Legs Syndrome
The SF-36 has now been used in two population-based studies identifying individuals with RLS symptoms. The evaluation of RLS prevalence among elderly in Augsburg, Germany, used a standard clinical interview with a neurologic examination. The 369 participants completed the SF-36. RLS was diagnosed for 36 subjects (9.8%). Those with RLS compared with those without RLS showed on the SF-36 significantly (p <.05) lower scores for the mental health and depression dimensions. Although the vitality and role-physical scores were also lower for RLS, the differences were not statistically significant,17 but this was a small sample of older individuals (65 to 83 years old) who already have some compromise in physical health and vitality limiting somewhat sensitivity of the measure on these domains.
